9513671 Milgram Cells are composed of a number of separate membrane bound structures. Each of these structures carries out a specific function, such as energy production, degradation of old and damaged proteins, and intercellular communication. The proper functioning of the cell depends upon the ability of the cell to direct each of its many thousands of proteins to the correct structure. There are many cells, including those in the brain and endocrine glands, which synthesize small chemical messengers called peptides. Once these small proteins are released into the intercellular space they find their way to target cells and bind to proteins imbedded in the surface of the recipient cell and initiate signaling. These peptides are derived from larger protein precursors which are packaged into packets for release called secretory granules. However, the mechanisms whereby proteins and peptides are targeted to secretory granules is unclear. The present work investigates the mechanisms used by proteins to insure their packaging in the proper secretory granules and will determine whether the amino acid sequences of the proteins contain information sufficient to direct the proteins to the correct intracellular organelle. This research will provide a greater understanding of how peptides are made and targeted to secretory granules in neuroendocrine cells. In addition, this work is essential for understanding how cells in all organisms use chemical messengers for communication and has applications to cell biologists beyond the neuroendocrine field.
